Goodwill and Other Intangible Assets - Schedule of Goodwill (Details) - USD ($) $ in Millions		12 Months Ended
		May 31, 2020	May 31, 2019	May 31, 2020	May 31, 2018
Net Goodwill Detail [Abstract]
Gross Goodwill at May 31					$ 8,657
Accumulated impairment charges				$ (2,042)	(1,684)
Goodwill		$ 6,884	$ 6,973	6,372	6,973
Goodwill Roll Forward
Beginning Goodwill at May 31		6,884	6,973
Goodwill acquired	[1]		126
Impairment charges		(358)
Other	[2]	(154)	(215)
Ending Goodwill at May 31		6,372	6,884
Accumulated impairment charges				(2,042)	(1,684)
Corporate, Other and Eliminations [Member]
Net Goodwill Detail [Abstract]
Gross Goodwill at May 31					1,950
Accumulated impairment charges				(1,909)	(1,551)
Goodwill		29	394	29	399
Goodwill Roll Forward
Beginning Goodwill at May 31		394	399
Impairment charges		(358)	0
Other	[2]	(7)	(5)
Ending Goodwill at May 31		29	394
Accumulated impairment charges				(1,909)	(1,551)
FedEx Express Segment [Member] | Operating Segments [Member]
Net Goodwill Detail [Abstract]
Gross Goodwill at May 31					5,100
Goodwill		4,869	5,016	4,869	5,100
Goodwill Roll Forward
Beginning Goodwill at May 31		5,016	5,100
Goodwill acquired	[1]		126
Other	[2]	(147)	(210)
Ending Goodwill at May 31		4,869	5,016
FedEx Ground Segment [Member] | Operating Segments [Member]
Net Goodwill Detail [Abstract]
Gross Goodwill at May 31					840
Goodwill		840	840	840	840
Goodwill Roll Forward
Beginning Goodwill at May 31		840	840
Ending Goodwill at May 31		840	840
FedEx Freight Segment [Member] | Operating Segments [Member]
Net Goodwill Detail [Abstract]
Gross Goodwill at May 31					767
Accumulated impairment charges				(133)	(133)
Goodwill		634	634	634	634
Goodwill Roll Forward
Beginning Goodwill at May 31		634	634
Ending Goodwill at May 31		$ 634	$ 634
Accumulated impairment charges				$ (133)	$ (133)

[1] Goodwill acquired relates to the acquisitions of Flying Cargo and the controlling interest in an existing joint venture with Swiss Post. See Note 3 for more information.

[2] Primarily currency translation adjustments, purchase price allocation-related adjustments, and acquired goodwill related to immaterial acquisitions.